Hard disk drives are common information storage devices. A typical disk drive unit essentially consists of a series of rotatable disks mounted on a spindle motor, and an HAA which is rotatable about an actuator arm axis for accessing data tracks on disks during seeking. The HAA includes at least one drive arm and an HGA. Typically, a spindling voice-coil motor (VCM) is provided for controlling the motion of the drive arm. The HGA includes a magnetic read write head that records information into the magnetic disk and reproduces information stored in the magnetic disk, and a suspension to load or suspend the magnetic read write head thereon.
For increasing the recording density of the magnetic disk, and meanwhile improving thermal stability of the magnetization of the magnetic microparticles in the magnetic disk, a so-called thermally assisted magnetic writing technology has been developed, recently. In this technology, a magnetic recording medium with large coercivity is used, and when information is written, heat is applied together with the magnetic field to a section of the magnetic recording medium where the information is to be written to increase the temperature and lower the coercivity of that section, thereby writing the information. Hereinafter, the magnetic head used in the thermally assisted magnetic writing is referred to as a thermally assisted magnetic write head.
In performing the thermally assisted magnetic writing, near field light is generally used for applying heat to a magnetic recording medium. In this technology, light propagating through a waveguide (guided light) is not directly applied to a plasmon generator, but the guided light is coupled to the plasmon generator through evanescent coupling, and surface plasmon polaritons generated on a surface of the plasmon generator are utilized. U.S. Pat. No. 7,330,404 proposes such a thermally-assisted head using surface plasmon polariton coupling.
The thermally assisted magnetic write head that utilizes the surface plasmon polariton suppresses a rise in temperature of the plasmon generator to some extent. However, it was confirmed that, when Au (gold) is used to configure the plasmon generator for example, there are cases where contraction (agglomeration) resulting from heat occurs especially in a section, near the ABS, where a volume is low and where the heat concentrates.
Such agglomeration is considered to be a phenomenon caused by gold configuring the plasmon generator not being in a stabled state such as a bulk state. That is, since gold formed through a plating method, a sputtering method, or the like is low in density, it is considered that a rise in temperature upon operation of the thermally assisted magnetic write head increases the density thereof, and a crystalline structure thereof advances toward a stabilized state.
Hence, it is desirable that a heat treatment be performed in advance during manufacturing to stabilize the crystalline structure of a material (such as gold) configuring the plasmon generator.
On the other hand, since the thermally-assisted magnetic write head is usually provided together with a magnetic read head that includes the MR element, it is desirable that a heat treatment at a temperature that thermally damages operation performance of the MR element be avoided. Therefore, sufficiently stabilizing a crystalline structure of a constituent material of the plasmon generator to sufficiently suppress the agglomeration thereof upon operation is virtually difficult. When such agglomeration occurs, an end section of the plasmon generator is recessed from the ABS and is away from a magnetic recording medium, incurring a decrease in recording performance.
Accordingly, it is desired to provide an improved thermally assisted magnetic write head capable of suppressing agglomeration of a plasmon generator upon operation, performing higher density magnetic recording.